Mitt Romney addressing the US Hispanic Chamber of Commerce in Los Angeles, in September; but Latino voters are expected to favour Obama by a margin of at least 30 points. Photograph: Nicholas Kamm/AFP/Getty Images

Barring a complete and systematic failure of pretty much every single polling organization in America, Barack Obama will be re-elected president of the United States Tuesday night.

Still, no matter what happens on Tuesday – and even if Mitt Romney pulls off the most extraordinary political surprise in the history of American presidential campaigns – the more than 18-month slog for the White House provides us with rather clear outlines on the changing nature of the US electorate and the ideological positioning of the two parties. While it would be incomplete and, indeed, probably incorrect to call this a realignment election, there are a number of crucial takeaways from campaign 2012 – and they augur much brighter days ahead for Democrats than for Republicans.

The Republican party's continued descent into madness

The single most defining element of American politics over the last four years is that the Republican party has fallen out of the crazy tree and hit every branch on the way down. It is no longer even appropriate to say the Republican party is dominated by its conservative wing; but rather, that the GOP is controlled by its extreme, radical wing.

The shift of the Republican to the far, far right is not a recent development. Instead, it is reflective of a four-decade shift in ideological orientation in the GOP: from a party once torn between distinct conservative and moderate wings, to one in which moderates have gone the way of dinosaurs and VCRs. But there is no question that in the past four years, the extremism of the GOP has increased dramatically – so much so that their most recent president, George W Bush, is persona non grata in the party because he is viewed as too moderate and not sufficiently conservative. Imagine that.

For years, the national Republican party emboldened this wing of the GOP and made it the vanguard of its efforts to maintain national power. That group now holds ideological sway in the Republican party. In the naked pursuit of short-term partisan gain, the Republican party has unleashed forces that it can no longer fully control.

The result is a set of policies that not only are radical, but also are out of step with the mainstream of American politics. This includes everything from efforts to privatize Medicare, eviscerating social security, rejecting any role for fiscal policy other than cutting taxes, and taking the position that illegal immigrants should not receive amnesty but rather "self-deport". This is not to mention the GOP's growing extremism on abortion rights and reproductive health in general.

Republicans once aspired to, and briefly held, the mantle of a party of ideas. Today, the GOP in its deference to the ideological rigidity of its radical wing has reached a position where Republicans have no serious ideas for reforming healthcare, creating jobs, stimulating the economy, or fixing the nation's crumbling infrastructure. They also have no proposals for achieving energy independence and certainly no thought as to how to save the planet – particularly since they reject almost unanimously the science underpinning global warming. (Well, I take that back: Republicans have one policy for all these issues – cut taxes and trim regulation.)

This has forced their party standard-bearer, a technocratic moderate from Massachusetts, to become a caricature of a modern conservative. In the process, Romney has adopted a host of toxic policy positions and rhetoric (remember the 47%) that has dramatically undermined his candidacy. It's always difficult to beat an incumbent president; it's even more difficult when you're not a very good politician. But when your own party hangs around your neck policy positions that narrow, rather than increase, your chances of being elected, it becomes a herculean task.

To be sure, one of the most important drivers of the Republican's rightward turn has been the unceasing obstructionism toward President Obama's agenda. From early on, the GOP decided that, for political reasons, it must oppose everything he wanted to do. It was an approach that kept the economy under-performing but did help return Republicans to power in the House of Representatives in 2010. Blanket opposition to Obama's policies and, in particular, economic stimulus is pretty much the only reason this election is even close.

If Obama is to win on 6 November, it's possible that Republicans will, at least in the near term, narrow their steadfast hostility to him. Indeed, even against their better judgment, they may find themselves compromising with the White House on the Bush tax cuts and sequestration, just as they compromised on the payroll tax cut in 2012, over the 2011 budget showdown and even on the debt limit.

Providing Obama with the stimulus he has so desperately sought, for the past four years, might even suddenly seem acceptable, particularly if a boost in the economy helps incumbent congressional Republicans keep their constituents happy – and their jobs in place, at the next midterm elections in 2014. Of course, that doesn't mean anyone should get their hopes up: Republicans will still continue to oppose any use of government power and resources to ameliorate social inequalities. And as we get closer to midterm elections in 2014, as well as the next presidential race, it's quite possible, even likely, that GOP obstructionism and obstinacy will get worse.

If Romney wins, congressional Republicans might be even less inclined to compromise, but it won't matter much. No one expects them to take back control of the Senate, which means the Republicans' far-right agenda will go no further than the House of Representatives (at least for the first two years of a Romney presidency). If Republicans were to take back the Senate in 2014 (a possibility that can't be completely discounted), this would be a very different story. One could expect them to make a desperate push to enact some variation of the Ryan budget – and probably succeed.

Still, one of the great ironies of this election – and the capture of the GOP by its extreme wing – is that if Romney were to emerge victorious, he would be protected from having to enact a more radically conservative agenda … by Harry Reid. In fact, if Romney were to win, he might even end up being a fairly popular and successful president.

Demographics are destiny

The problem for Republicans, however, is what happens if he loses. In no area of American politics are Republicans more vulnerable and Democrats in better position to capitalize than when it comes to the country's changing demographic make-up.

Consider, for a moment, this paradox. On Tuesday night, Barack Obama could potentially lose white voters by 20 points. He's going to get crushed among white men – and he's still likely to be re-elected, maybe even comfortably.

The reason for this is clear: among non-whites, Obama enjoys an extraordinary advantage. Aside from winning practically the entire African-American vote, Obama is likely to prevail among Hispanic voters by considerably more than 30 points. The latest Latino Decisions poll has him up nearly 50 points.

Among younger voters, he is likely to dominate as well. In short, among the demographic groups that represent the future of the American electorate, Democrats enjoy an enormous edge – and one that will only become more pronounced.

It's not hard to understand why this has happened. Young people who came of age in the Bush years naturally gravitated toward Obama. Moreover, these voters tend to be aligned on social issues with Democrats. On the flip side, GOP positions on immigration have alienated Hispanics and moved them toward the Democrats. Beyond young people and minorities, women voters have increasingly turned their back on the GOP because of its uncompromising stances on abortion and reproductive health, as well as the party's attitude toward poverty programs and maintaining the social safety net.

Republicans have, for decades, relied on the support of whites, religious and cultural voters, and on rural residents. If Obama were to win Tuesday, it would provide conclusive evidence that this is no longer a 50.1% coalition – and that for Republicans to win back the presidency, they must broaden their share of the electorate.

But here's the rub: there is no easy way for them to do it. Even if Republicans could find a way to work with Obama on an issue like immigration reform (an unlikely scenario considering the die-hard opposition of the Tea Party), a legislative victory for the president would only serve to strengthen his support in the Hispanic community. If Republicans oppose reform, however, they will only dig their hole deeper with the fastest growing demographic group in the country. In fact, if Obama were smart, he would make the Dream Act and comprehensive immigration reform one of his first legislative priorities in 2013.

On abortion and reproductive health, it's virtually impossible to imagine any sort of compromise coming from the GOP. And so long as the party has Senate candidates talking about "legitimate rape" and children born as a result of rape being gifts from God, things are likely to get worse for the Republican party, before they get better. The same goes for gay marriage and other social issues.

A bluer map

The Democrats' evolving political coalition has also shifted the electoral map in a bluer direction. In states like Nevada and New Mexico, Democrats enjoy a huge advantage because of those states' large Hispanic population. Similar trends can be seen in Colorado, Florida and even Iowa. It is not hard to imagine that Democratic dominance among Hispanic voters will soon put Arizona and even, potentially, Texas in play.

In places like Ohio, Virginia and North Carolina, the Democrats' overwhelming advantage among minority voters and, increasingly, among college-educated whites – another key element of the emerging Democratic coalition – has put these states into play and even leaning blue.

Flip the map for a second to look at it from a Republican perspective and things get ugly quickly. Look, for example, at the 2000 electoral map. Of the states won by Al Gore that year, only Iowa and perhaps Wisconsin are even in play this cycle. Conversely, seven states that Bush won that year are swing states or leaning Democratic. From a starting point of 271 electoral votes (one more than the bare minimum needed to win a national election), Republicans have seen their electoral map narrow rather than widen.

A recovering economy

There is one final consideration. As the economy has steadily improved, so, too, have President Obama's approval ratings. All economic indicators indicate that this will be a continuing trend, which means that if Obama were to win Tuesday, he would see his political standing rise as unemployment continues to fall. (Of course, if Romney were to win, he would be the beneficiary of this improving economy.) Throw in the fact that as Obamacare becomes the law of the land and provides a new entitlement for middle-class Americans, the Democrat's long-term policy advantage could be strengthened even further.

None of this is meant to suggest that Republicans won't continue to be a competitive national party. The problem, however, is similar to that faced by Democrats 20-30 years ago: when your base is shrinking, how do you appeal to a broader cross-section of the electorate?

The fact is, there is no easy way for Republicans do it. The GOP needs desperately to reform itself, to cast aside its most radical and extreme wing, and to moderate its policies to appeal to an electorate that is dramatically changing. Democrats simply need to continue the policies – and political approach – that has given them a political advantage going into election day.

What this means is that, should Romney lose tomorrow and Obama emerge victorious, we may be on the cusp of a dramatic shift in national politics.